Bright and highly valley polarized trions in chemically doped monolayer MoS2

Abstract

We demonstrate the effect of p-Type dopant F4TCNQ molecular adsorption on the photoluminescence (PL) and valley polarization properties of trions in monolayer (1L) MoS2 at 15 K using a spatial PL mapping method. Trion PL intensity considerably increased after the treatment, which was attributed to the extended trion nonradiative lifetime (∼70 ps). Trion valley polarization as high as 0.75 showed a negligible decrease after the chemical treatment, as is the manifestation of a long trion valley lifetime of more than nanoseconds order. The results suggest that this method will be useful for future optovalleytronics applications of these materials.